One uncommon place where clipping
is justified at the design level: lazy-loading of finite but known-size lists, with a real and correct scrollbar. I’ll use Fastmail’s webmail (on which I worked a few years back) as an example. I could load a list of a hundred thousand emails, and each message in the list is, under my configuration, 88px tall (containing four lines of text—approximately, sender and date, subject, and two lines of preview, with truncation on each), so the list container is made to be 8,800,000 pixels high¹, and I can use its scrollbar to immediately jump to any place, and it will figure out which messages to fetch and render based on the scroll position.
If the subject line were wrapped, which would be nice at times, you’d lose this ability: you’d have to guess the approximate height of each element, and your scroll positions will be imprecise and you’ll have to make messy adjustments from time to time. Overall it generally won’t be too bad so long as there’s not too much variation in them, but it’s definitely still inferior.
You can then read the full subject line and other truncated fields either by opening the email, or by hovering, as the full text is set as the tooltip. And here’s a general tip for others: if you do ever automatically truncate overflowing text, you should set the element’s tooltip to the full text.
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¹ Browser do have limits on how large you can make containers, and handle excess in different ways. IE had the lowest threshold of failure at around ten million pixels, beyond which point it would ignore values; the workaround I implemented in https://github.com/fastmail/overture/commit/8d01c74d8c5d4ae0... came as a direct result of a customer reporting that scrolling was broken in IE in their mailbox with a couple of hundred thousand emails. Firefox breaks a little after 2²⁴ pixels, also ignoring values, so it’s still covered in https://github.com/fastmail/overture/blob/0c9828a5b77ad14383... (note the IE stuff is gone because IE is dead! :-) ). WebKit-heritage browsers accept larger values, but clamp them to about 2²⁵ pixels. In all cases, the clamping solution means you can’t access the emails at the end of the list. C’est la vie.